Can Mac and Windows users play in the same Killing Floor game

What is a good strategy for quickly leveling perks that gain experience through damage? The perks I'm talking about are Support Specialist, Berserker, Firebug, and Demolitions.

Don't play single-player please. It's not very fun, and you will not learn from other people. Most of these tips to follow, I've gained through watching other people play. The best advice I can give you is to find out what your perk specializes in and do that. Don't do things your perk is not great at :)

Support Specialist

• Weld doors if your team holes up somewhere.
• Aim for the head. Shotguns penetrate through several enemies much easier if you aim for the head instead of the chest.
• Crouch when you see crawlers (everyone hates those nasty little turds)
• Don't buy armor/grenades/pistol ammo for the first 4-5 waves in order to save up for an AA12. This is good advice for other classes too.

Berserker

• If your team holes up somewhere, you should be at the front, soaking in the damage. Everything should attack you first. You should get a decent medic (get a mic and use it, it makes life much easier)
• You can stun certain enemies, especially scrakes. This is important -- read up on kf-wiki.com how to do it.
• Learn to know when you're getting screwed. You move fast as a zerker so you can run away -- just be sure to run away before being really screwed :)

Firebug

• Religiously leave "big" things like scrakes and fleshpounds to other perks. Just run away :)
• Watch when your friendlies are getting screwed and unload your whole canister into them. Demolition players especially will love you if you help them out when they're screwed and overran by small things.
• Don't annoy your team with flames -- it really makes it hard to aim and it blurs everyone's vision. Stand away from friendlies (pick an "entrance" to your camping spot and cover it on your own, or use the MAC10)
• You make a ton of money as firebug -- spread the love. No use dying rich :)

Demolition

• This one is tough -- leave it for later if you can. It's expensive and somewhat hard to play.
• Always stay behind friendlies -- you have very little "close quarter" killing abilities.
• It's best if your team camps in a spot. Stand on top of a car or gain elevation in any way, and then shoot for clumps of small things.
• Use the M79 (single-shot) as primary, and leave M32 for when your team faces a scrake/fleshpound.

General advice :)

• Use a microphone, even if just for yelling out "scrake" or "fleshpound" or "need help please"
• Ask for how much money you need, not that you need money. You're way more likely to get money if you say how much you want.
• Stick to your team :)
• Look for weapons to sell -- most of your "advanced" weapons cost a lot of money, so save like a scrooge.
• Learn how to kite a lot of enemies -- if you're screwed, cut your way out, and run like a .. female canine. Then, let them follow you, and pick 'em off one by one.
• Look at how other people are using a perk. Most of the advice above is from seeing what other people do and doing it myself. I've got most classes to 5 or 6, so I've picked up a bunch of tricks from people.

Enjoy yourself! Don't worry too much about playing on other difficulties, you'll get there eventually. Have fun with where you are.

Scrakes are the enemies that chase you around with a chainsaw.

I haven't had a chance to play Killing Floor yet since the update, but if it's anything like the Christmas update, Circus Scrakes have replaced regular Scrakes in every level.

According to the KF Wiki:

For the Summer Sideshow he was reskinned into "the Incredible man monkey", a giant cymbal monkey, this time retaining the chainsaw arm.

I believe they start appearing in the fifth wave during a Long game, third during a Medium game.

The Crossbow is sold by the in-game vendor for £800.